<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<script>
    let a={
        name: '张三'
    }

    function fn(obj){
        obj.name = '李四';
    }

    fn(a)

    console.log(a.name)  //李四


    let b=3
    function fn2(obj){
        obj=obj+2;
        console.log(obj)
    }

    fn2(b)
    console.log(b)
    
</script>
</body>
</html>